:root {
      --primary-color: #4f46e5;
      --primary-gradient: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
      --accent-gradient: linear-gradient(135deg, #f43f5e 0%, #fb923c 100%);
      --bg-light: #f8fafc;
      --card-bg: #ffffff;
      --text-main: #0f172a;
      --text-muted: #475569;
      --border-color: #e2e8f0;
      --container-max: 1200px;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
      --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
      --shadow-lg: 0 10px 25px -5px rgba(79, 70, 229, 0.15);
      --radius: 12px;
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    html {
      scroll-behavior: smooth;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
      background-color: var(--bg-light);
      color: var(--text-main);
      line-height: 1.6;
    }

    body {
      overflow-x: hidden;
    }

    a {
      color: var(--primary-color);
      text-decoration: none;
      transition: opacity 0.2s ease;
    }
    a:hover {
      opacity: 0.85;
    }

    .container {
      width: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 20px;
    }

    /* 顶部导航 */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 1000;
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(10px);
      border-bottom: 1px solid var(--border-color);
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 70px;
    }
    .brand {
      display: flex;
      align-items: center;
      gap: 12px;
    }
    .brand img {
      max-height: 40px;
      width: auto;
    }

    /* Mandatory Rule: .nav-links gap must be 0 */
    .nav-links {
      display: flex;
      align-items: center;
      gap: 0;
      list-style: none;
    }
    .nav-links li a {
      padding: 8px 12px;
      font-size: 14px;
      font-weight: 500;
      color: var(--text-main);
      display: inline-block;
      transition: color 0.2s ease;
    }
    .nav-links li a:hover {
      color: var(--primary-color);
    }

    .header-actions {
      display: flex;
      align-items: center;
      gap: 12px;
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 20px;
      border-radius: 8px;
      font-size: 14px;
      font-weight: 600;
      cursor: pointer;
      border: none;
      transition: all 0.25s ease;
      white-space: nowrap;
    }
    .btn-primary {
      background: var(--primary-gradient);
      color: #ffffff;
      box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
    }
    .btn-primary:hover {
      transform: translateY(-2px);
      box-shadow: 0 6px 16px rgba(79, 70, 229, 0.4);
      color: #ffffff;
    }
    .btn-secondary {
      background: #ffffff;
      color: var(--primary-color);
      border: 1px solid var(--primary-color);
    }
    .btn-secondary:hover {
      background: var(--bg-light);
    }

    .nav-toggle {
      display: none;
      background: none;
      border: none;
      font-size: 24px;
      cursor: pointer;
      color: var(--text-main);
    }

    /* Section Global */
    .section {
      padding: 70px 0;
    }
    .section-title-wrap {
      text-align: center;
      max-width: 800px;
      margin: 0 auto 45px auto;
    }
    .badge {
      display: inline-block;
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 600;
      background: rgba(79, 70, 229, 0.1);
      color: var(--primary-color);
      margin-bottom: 12px;
      text-transform: uppercase;
    }
    .section-title {
      font-size: 32px;
      font-weight: 800;
      letter-spacing: -0.5px;
      margin-bottom: 12px;
      color: var(--text-main);
    }
    .section-subtitle {
      font-size: 16px;
      color: var(--text-muted);
    }

    /* Hero 区域 (无图片) */
    .hero-section {
      padding: 90px 0 70px 0;
      background: linear-gradient(180deg, #e0e7ff 0%, #f8fafc 100%);
      text-align: center;
      position: relative;
    }
    .hero-content {
      max-width: 900px;
      margin: 0 auto;
    }
    h1.hero-h1 {
      font-size: 40px;
      font-weight: 900;
      line-height: 1.25;
      margin-bottom: 20px;
      background: var(--primary-gradient);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }
    .hero-desc {
      font-size: 18px;
      color: var(--text-muted);
      margin-bottom: 30px;
      line-height: 1.7;
    }
    .hero-btns {
      display: flex;
      justify-content: center;
      gap: 16px;
      margin-bottom: 40px;
      flex-wrap: wrap;
    }
    .hero-btn-official {
      padding: 14px 32px;
      font-size: 16px;
    }
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      margin-top: 40px;
    }
    .stat-card {
      background: var(--card-bg);
      padding: 24px;
      border-radius: var(--radius);
      box-shadow: var(--shadow-md);
      border: 1px solid var(--border-color);
      transition: transform 0.3s ease;
    }
    .stat-card:hover {
      transform: translateY(-4px);
    }
    .stat-num {
      font-size: 32px;
      font-weight: 800;
      color: var(--primary-color);
    }
    .stat-label {
      font-size: 14px;
      color: var(--text-muted);
      margin-top: 4px;
    }

    /* Grid Layouts */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
    }
    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 30px;
    }

    /* Cards & Components */
    .card {
      background: var(--card-bg);
      border-radius: var(--radius);
      padding: 28px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
      transition: all 0.3s ease;
    }
    .card:hover {
      box-shadow: var(--shadow-lg);
      transform: translateY(-4px);
    }
    .card-icon {
      width: 48px;
      height: 48px;
      border-radius: 10px;
      background: var(--primary-gradient);
      color: #fff;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 20px;
      font-weight: bold;
      margin-bottom: 16px;
    }
    .card-title {
      font-size: 18px;
      font-weight: 700;
      margin-bottom: 10px;

    }
    .card-desc {
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.6;
    }

    /* Model Matrix Tags */
    .model-tags {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      justify-content: center;
      margin-top: 20px;
    }
    .tag-chip {
      background: #ffffff;
      border: 1px solid var(--border-color);
      padding: 8px 16px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 600;
      color: var(--text-main);
      box-shadow: var(--shadow-sm);
    }

    /* Step Process */
    .process-step {
      text-align: center;
      position: relative;
    }
    .step-num {
      width: 40px;
      height: 40px;
      border-radius: 50%;
      background: var(--accent-gradient);
      color: white;
      font-weight: 800;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 0 auto 16px auto;
    }

    /* Evaluation Table */
    .eval-box {
      background: #fff;
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      overflow: hidden;
      box-shadow: var(--shadow-md);
    }
    .eval-header {
      background: var(--primary-gradient);
      color: #fff;
      padding: 20px 30px;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .eval-score {
      font-size: 36px;
      font-weight: 900;
      line-height: 1;
    }
    .eval-stars {
      color: #fbbf24;
      font-size: 20px;
    }
    .table-responsive {
      width: 100%;
      overflow-x: auto;
    }
    .custom-table {
      width: 100%;
      border-collapse: collapse;
      text-align: left;
    }
    .custom-table th, .custom-table td {
      padding: 16px 20px;
      border-bottom: 1px solid var(--border-color);
      font-size: 14px;
    }
    .custom-table th {
      background: #f1f5f9;
      font-weight: 700;
    }

    /* FAQ Accordion */
    .faq-container {
      max-width: 900px;
      margin: 0 auto;
    }
    .faq-item {
      background: #fff;
      border: 1px solid var(--border-color);
      border-radius: 8px;
      margin-bottom: 12px;
      overflow: hidden;
    }
    .faq-question {
      padding: 18px 24px;
      font-weight: 700;
      font-size: 16px;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      background: #fff;
      user-select: none;
    }
    .faq-answer {
      padding: 0 24px 18px 24px;
      font-size: 14px;
      color: var(--text-muted);
      display: none;
      line-height: 1.7;
    }
    .faq-item.active .faq-answer {
      display: block;
    }
    .faq-item.active .faq-toggle-icon {
      transform: rotate(180deg);
    }

    /* Media Images Responsive */
    .ai-page-image {
      border-radius: 8px;
      margin-bottom: 12px;
      box-shadow: var(--shadow-sm);
    }
    .media-showcase-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }

    /* Article List */
    .article-list {
      list-style: none;
      background: #fff;
      border-radius: var(--radius);
      padding: 20px;
      border: 1px solid var(--border-color);
    }
    .article-list li {
      padding: 12px 0;
      border-bottom: 1px dashed var(--border-color);
      display: flex;
      justify-content: space-between;
    }
    .article-list li:last-child {
      border-bottom: none;
    }

    /* Reviews Section */
    .review-author {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-top: 16px;
    }
    .avatar-placeholder {
      width: 40px;
      height: 40px;
      border-radius: 50%;
      background: var(--primary-gradient);
      color: white;
      font-weight: bold;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    /* Contact & Form */
    .contact-wrapper {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      background: #fff;
      border-radius: var(--radius);
      padding: 40px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-md);
    }
    .form-group {
      margin-bottom: 18px;
    }
    .form-group label {
      display: block;
      font-size: 14px;
      font-weight: 600;
      margin-bottom: 6px;
    }
    .form-control {
      width: 100%;
      padding: 10px 14px;
      border: 1px solid var(--border-color);
      border-radius: 6px;
      font-size: 14px;
    }
    .form-control:focus {
      outline: none;
      border-color: var(--primary-color);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
    }

    /* Footer Safety Color: Light background with Dark Text as required */
    .site-footer {
      background: #f1f5f9;
      color: #334155;
      padding: 50px 0 25px 0;
      border-top: 1px solid var(--border-color);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 30px;
      margin-bottom: 40px;
    }
    .footer-col h4 {
      font-size: 16px;
      font-weight: 700;
      color: #0f172a;
      margin-bottom: 16px;
    }
    .footer-links {
      list-style: none;
    }
    .footer-links li {
      margin-bottom: 8px;
    }
    .footer-links a {
      color: #475569;
      font-size: 14px;
    }
    .footer-links a:hover {
      color: var(--primary-color);
    }
    .friend-links-box a {
      display: inline-block;
      margin-right: 12px;
      margin-bottom: 8px;
      color: #475569;
      font-size: 13px;
    }
    .footer-bottom {
      border-top: 1px solid #cbd5e1;
      padding-top: 20px;
      text-align: center;
      font-size: 13px;
      color: #64748b;
    }

    /* Floating Widget */
    .floating-widget {
      position: fixed;
      bottom: 30px;
      right: 30px;
      z-index: 999;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }
    .float-btn {
      width: 50px;
      height: 50px;
      border-radius: 50%;
      background: var(--primary-color);
      color: white;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 4px 12px rgba(0,0,0,0.15);
      cursor: pointer;
      font-weight: bold;
      font-size: 12px;
      text-align: center;
    }

    @media (max-width: 992px) {
      .grid-4, .grid-3, .stats-grid, .media-showcase-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .contact-wrapper, .footer-grid {
        grid-template-columns: 1fr;
      }
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 20px;
        box-shadow: var(--shadow-md);
        border-bottom: 1px solid var(--border-color);
      }
      .nav-links.active {
        display: flex;
      }
      .nav-toggle {
        display: block;
      }
      .grid-2, .grid-3, .grid-4, .stats-grid, .media-showcase-grid {
        grid-template-columns: 1fr;
      }
      h1.hero-h1 {
        font-size: 28px;
      }
    }